1. Field of the Invention
The invention relates to a rotational vibration damper provided, particularly, for arrangement in a drive train of a motor vehicle driven by an internal combustion machine.
2. Description of the Related Art
A prior art rotational vibration damper is disclosed in German reference DE 42 00 174 A1. The rotational vibration damper is disclosed as a dual-mass flywheel of a friction clutch, comprising two centrifugal masses rotatable together as well as relative to each other around a common rotational axis. One of the centrifugal masses is an input component and the other of the centrifugal masses is an output component of the rotational vibration damper. The two flymasses are connected for the purpose of transmitting rotational forces by a plurality of coupling masses distributed evenly around the rotational axis. Each of the coupling masses has a pendulum weight pivotally connected to the first flymass about a pivot axis which is offset relative to the rotational axis in axis-parallel fashion. The center of gravity of the pendulum weight lies outside of the pivot axis. If no torque is transmitted when the rotational vibration damper is rotated around the rotational axis, the pendulum weight, by virtue of the centrifugal force acting up it, is arranged relative to the first flymass in such a way that the center of gravity of the pendulum weight lies on a common plane with the pivot axis and the rotational axis. A substantially circumferentially oriented elongated connecting element is arranged around the rotational axis to transmit rotational forces from the pendulum weight to the second flymass. The elongated connecting element is connected, on one side, to the second flymass and, on the other side, at a point radially outside of the pivot axis, to the pendulum weight. During operation, a torque to be transmitted between the two flymasses attempts, by introducing a rotational force via this connecting element, to rotate the connecting element around the pivot axis relative to the first flymass against the action of the centrifugal force, whereby the two flymasses also rotate relative to each other. At a constant torque to be transmitted, the pendulum weight assumes a position of equilibrium relative to the first flymass at which the centrifugal force and the rotational force counterbalance each other. The centrifugal force attempts to orient the center of gravity of the pendulum weight radially relative to the pivot axis and the rotational force introduced via the connecting element attempts to orient the center of gravity of the pendulum weight in the circumferential direction. If fluctuations occur in the torque to be transmitted, the pendulum weight is pivoted around the equilibrium position on both sides and thereby allows the two flymasses to rotate relative to each other. As a result of pivoting, the rotational vibrations occurring between the two flymasses are damped. The relative rotation of the two flymasses counteracts an inertial force of the pendulum weight that resists a pivoting of the pendulum weight due to the inertial moment of the pendulum weight relative to the pivot axis. The resistance to pivoting provided by the inertial moment lends necessary rigidity to the rotational vibration damper.
The rotational vibration damping properties of the rotational vibration damper are substantially determined by the mass distribution of the pendulum weight; the distance between the center of gravity of the pendulum weight and the pivot axis; the distance between the pivot axis and the rotational axis; and the length of the connecting element. By changing these distances and the mass distribution, it is possible to change the rotational vibration damping properties within a certain framework. However, the possibilities for adjusting as desired the curve of the transmitted torque based on the rotational deflection of the two flymasses relative to each other are limited.